Electric shower problem

[thesmoothound]

Hi.
I recently replace cistern in down stairs toilet and as a result had water hammer. I read up on this and was advise to switch off mains pressure water, open all outlets upstairs and then downstairs. And then switch on mains and switch on outlets in reverse order. This worked and no water hammer. However, now, when using electric shower and someone switches another tap on, the shower goes from very hot to cold and the water pressure is all over the place. This was never like this before. You noticed a slight pressure drop but nothing like it is now. I have a combination boiler. Please can someone offer some advice. Thank you.

 

[Newboy]

Is the mains stopcock fully open?

Sounds like the flowrate through the stopcock has reduced

 

[thesmoothound]

Hi. Stopcock is only open a quarter as that is what it was before closed it. I will open fully and see if it improves. Thank you.

 

[Stadan20]

That’s electric showers for ya ,,, open a tap and the flow rate will drop hence going hot then cold